The lowest temperature of a day generally occurs early in the
The lowest temperature of a day generally occurs early in the morning, around sunrise.
This is because, during the night, in the absence of the sun, heat has been continuously lost by the Earth in a steady manner. Because of this the temperature drops. When the sun rises, it's rays do not reach us directly or aren't hot enough to make a difference to the heat loss that has been going on and as a result, the temperature continues to fall further. Once the sun's rays are hot enough and start becoming more direct, the temperature will begin to increase once again.